derivatives of artemisinin, and their uses in the treatment of malaria

ABSTRACT

A new artemisinin derivatives, of following general formula (I): 
     
       
         
         
             
             
         
       
     
     In which:
         a and b are a single or a double bond,   n1 and n2 are 0 or 1,   R 1  is a fluoroalkyl group or a fluoroaryl group,   R 2  is a hydrogen atom, or a halogen atom, or a group, if appropriate ionisable, making it possible to render said compounds of formula (I) water-soluble,   R 3  is a group, if appropriate ionisable, making it possible to render said compounds of formula (I) water-soluble,   R 4  is H or OH. The invention also relates to the process by which they are obtained, and their uses in pharmaceutical compositions intended for the treatment of malaria.

The present application is a divisional of application Ser. No. 10/493,576, filed Oct. 5, 2004, now allowed, which is a 371 National Stage of international application no. PCT/FR2002/03675, filed Oct. 25, 2002, which claims priority to French application no. 01/13869, filed Oct. 20, 2001. The entire contents of the above-referenced applications are hereby incorporated by reference in their entirety.

A subject of the present invention is new derivatives of artemisinin, a process for obtaining them, and their uses in pharmaceutical compositions intended for the treatment of malaria.

The rapid development of the phenomenon of resistance to anti-malarial drugs is particularly alarming because of its considerable consequences in Africa and South-East Asia. New medicaments must urgently be discovered for the treatment of malaria from multi-drug resistant Plasmodium falciparum.

In addition to the current need for effective malarial therapies, are added the mandatory costs linked with the localization of the epidemic in poorer countries. Artemisinin is a natural, inexpensive compound, extracted from a plant Artemisia annua, used in traditional Chinese medicine against malaria.

Artemisinin (ART) has appeared to be a promising medicament against these resistant strains; its effectiveness is however limited by a very short plasmatic half-life, and low activity by oral route.

By taking into account the specific properties provided by the presence of fluorinated groups (Rf), the Inventors have conceived and prepared fluorinated analogues of dihydroartemisinin (DHA) by hemisynthesis, by introducing a fluoroalkyl group on the strategic C-10 carbon, in order to slow down the various processes of the metabolism (oxidation, hydrolysis and glucuronidation) which take place on this site and thus to prolong the duration of the action of the compounds (Truong Thi Thanh Nga et al., 1998, J. Med. Chem., 41, 4101-4108). These fluoro artemisinins (F-ART) are more active than artemisinin and artesunate in vivo in mice. The survival rate is 100%. The preliminary results of pharmacokinetic studies seem to validate the hypothesis on the extension of the plasmatic half-life of an artemisinin derivative by the introduction of a fluorinated substituent on the C-10 site.

The problem of the insolubility in water of these compounds which limits the effectiveness of administration by oral route remains to be solved. A new generation of fluorinated derivatives of artemisinin had to be envisaged and synthesis found allowing the presence of a fluoroalkyl group in C-10 and the introduction of a function, which is if appropriate ionisable (amine, acid etc.), making it possible to render these compounds water-soluble.

The present invention follows on from the highlighting by the Inventors, that it is possible to prepare new artemisinin derivatives, substituted both by a fluoroalkyl group in C-10, which has proved to extend the period of action of artemisinin, and by a function, if appropriate ionisable, on the carbon in position 10 or 16, which allows solubility in water and therefore easy administration by oral route.

The present invention has consisted of finding a chemical means of introducing an ionisable function on artemisinin derivatives fluorinated in C-10. Difficulties in synthesis have resided in the following facts: i) The starting products have few anchorage points allowing the introduction of new functions without harming activity; ii) The presence of fluorine in the molecules considerably alters its chemical reactivity.

The inventors have been able to resolve the problem, by preparing allylic bromide in C-9, a key product which allows the introduction of any other function, and thus by using inexpensive chemical reagents. Compounds which are water-soluble allow administration by oral route, which facilitates the treatment of malaria.

The invention relates to compounds of following general formula (I):

In which:

-   -   a and b represent a single or a double bond, provided that a and         b can not both represent a double bond,     -   n1 and n2, independently from one another, represent 0 or 1,         provided that when a represents a double bond then n1=n2=0 and         when b represents a double bond then n1=0,     -   R₁ represents:         -   A fluoroalkyl group of approximately 1 to approximately 5             carbon atoms, and comprising at least two fluorine atoms,             such as the following perfluoroalkyl groups: CF₃, C₂F₅,             C₃F₇, C₄F₉, and C₅F₁₁,         -   Or a fluoroaryl group comprising at least two fluorine             atoms, such as the C₆F₅ perfluoroaryl group,         -   Or a CF₂ group when b represents a double bond and n1=0,     -   R₂ represents a hydrogen atom, or a halogen atom, such as Br, or         a group, if appropriate ionisable, making it possible to render         said compounds of formula (I) water-soluble, such as the groups         derived from piperazine, morpholine, alkylamine, alkoxy, ester         or diester, acid or diacid, thioalkyl, alkylhydroxyl, or         glycosyl,     -   R₃ represents a group, if appropriate ionisable, making it         possible to render said compounds of formula (I) water-soluble,         such as:         -   An OR group in which R represents H, or an alkyl group of             approximately 1 to 10 carbon atoms, if appropriate             substituted, in particular a group of formula —(CH₂)_(n)—R₅             in which n represents an integer from 1 to 5, and R₅             represents: CF₃, OH, —CH═CH₂, COOH, COH, CHOH—CH₂OH, or a             phenyl group, if appropriate substituted, in particular by             CH₂OH,         -   NH₂, or a NH—R₆ group in which R₆ represents an alkyl or             alkoxy group of 1 to 5 carbon atoms, or an arylalkyl or             arylalkoxy group, such as the —NH—C₆H₅—OCH₃,     -   R₄ represents H or OH.

A more particular subject of the invention is compounds of general formula (Ia) corresponding to abovementioned formula (I) in which a represents a double bond, b represents a single bond, and n1=n2=0, namely compounds of following formula:

In which:

-   -   R₁ represents:         -   A fluoroalkyl group of approximately 1 to approximately 5             carbon atoms, and comprising at least two fluorine atoms,             such as the following perfluoroalkyl groups: CF₃, C₂F₅,             C₃F₇, C₄F₉, and C₅F₁₁,         -   Or a fluoroaryl group comprising at least two fluorine             atoms, such as the perfluoroaryl group C₆F₅,     -   R₂ represents a halogen atom, such as Br, or a group, if         appropriate ionisable, making it possible to render said         compounds of formula (I) water-soluble, such as the groups         derived from piperazine, morpholine, alkylamine, alkoxy, ester         or diester, acid or diacid, thioalkyl, alkylhydroxyl, or         glycosyl,

A subject of the invention is also the compounds of formula (Ia-bis), corresponding to the abovementioned compounds of formula (I) in which R₂ represents a group, if appropriate ionisable, making it possible to render said compounds water-soluble.

A more particular subject of the invention is the compounds of formula (Ia-bis) in which R₂ represents:

-   -   A group derived from piperazine, if appropriate substituted by         an amine, alcohol, or acid function, such as the piperazine         ethanol group of formula,

-   -   Or a morpholino group of formula,

-   -   Or an alkylamine group of approximately 1 to approximately 10         carbon atoms, if appropriate substituted by a hydroxyl, such as         the ethylamine group of formula —NH—CH₂—CH₃, or the         —NH—CH₂—CH₂—OH group,     -   Or an alkoxy group of approximately 1 to approximately 10 carbon         atoms, if appropriate substituted by a hydroxyl or amine         function, such as the ethoxy group of formula —O—CH₂—CH₃, the         —O—CH₂—CH₂—OH group, or the —O—CH₂—CH₂—NHR group in which R         represents an alkyl group of 1 to 5 carbon atoms,     -   Or an alkyl group of approximately 1 to approximately 10 carbon         atoms, substituted by one or more —COOR functions in which R         represents H or an alkyl, alkylamine, or alkylhydroxy group, of         approximately 1 to approximately 4 carbon atoms, such as the         group of formula

in which R_(a) and R_(b) represent H or CH₃,

-   -   or a thioalkyl group of approximately 1 to approximately 6         carbon atoms, such as the group of formula —S—CH₂—CH₃,     -   or an alkylhydroxyl group of approximately 1 to approximately 10         carbon atoms,     -   or a glycosyl group such as glucuronic acid or other         nonasaccharides.

The invention more particularly relates to the abovementioned compounds, of formula (I) or (Ia) in which R₁ represents CF₃, C₂F₅, C₃F₇, or C₆F₅.

A more particular subject of the invention is the abovementioned compounds of formula (Ia), corresponding to the following formulae:

The invention also relates to compounds, of general formula (Ib) corresponding to formula (I) in which a and b represent a single bond, and n1=n2=1, namely compounds of following formula:

In which:

-   -   R₁ represents:         -   A fluoroalkyl group of approximately 1 to approximately 5             carbon atoms, and comprising at least two fluorine atoms,             such as the following perfluoroalkyl groups: CF₃, C₂F₅,             C₃F₇, C₄F₉, and C₅F₁₁,         -   Or a fluoroaryl group comprising at least two fluorine             atoms, such as the perfluoroaryl group C₆F₅,     -   R₂ represents a hydrogen atom, or a halogen atom, such as Br, or         a group, if appropriate ionisable, making it possible to render         said compounds of formula (I) water-soluble, such as the groups         derived from piperazine, morpholine, alkylamine, alkoxy, ester         or diester, acid or diacid, thioalkyl, alkylhydroxyl, or         glycosyl,     -   R₃ represents:         -   An OR group in which R represents H, or an alkyl group of             approximately 1 to 10 carbon atoms, if appropriate             substituted, in particular a group of formula —(CH₂)_(n)—R₅             in which n represents an integer from 1 to 5, and R₅             represents: CF₃, OH, —CH═CH₂, COOH, COH, CHOH—CH₂OH, or a             phenyl group, if appropriate substituted, in particular by             CH₂OH,         -   NH₂, or a NH—R₆ group in which R₆ represents an alkyl or             alkoxy group of 1 to 5 carbon atoms, or an arylalkyl or             arylalkoxy group, such as the —NH—C₆H₅—OCH₃,     -   represents H or OH.

A more particular subject of the invention is compounds of above-mentioned general formula (Ib) in which R₁ represents CF₃, R₂ and represent a hydrogen atom, and R₃ is such as defined above, namely compounds of following formula:

The invention more particularly relates to compounds of abovementioned formula (Ib), corresponding to following formulae:

A subject of the invention is also compounds of general formula (Ic) corresponding to abovementioned formula (I), in which a represents a single bond, b represents a double bond, n1=0, n2=1, namely compounds of following formula:

In which:

-   -   R₁ represents a CF₂ group,     -   R₂ represents a hydrogen atom, or a halogen atom, such as Br, or         a group, if appropriate ionisable, making it possible to render         said compounds of formula (I) water-soluble, such as the groups         derived from piperazine, morpholine, alkylamine, alkoxy, ester         or diester, acid or diacid, thioalkyl, alkylhydroxyl, or         glycosyl,     -   R₄ represents H or OH.

A more particular subject of the invention is the compound of above-mentioned formula (Ic), of following formula:

The invention also relates to any pharmaceutical composition characterized in that it comprises at least one compound of formula (Ia) defined above, and more particularly of formulae (Ia-bis), (Ib), and (Ic), combined with a pharmaceutically acceptable vehicle.

The pharmaceutical compositions of the invention are advantageously presented in a form intended for administration by oral, injectable, or rectal route.

Preferably, the pharmaceutical compositions of the invention are characterized in that the unit dose of compounds of formula (I) as active ingredient of said compositions, is approximately 5 mg, to approximately 5 g, for a dosage of approximately 1 mg/kg/day to approximately 100 mg/kg/day.

The invention also relates to any pharmaceutical composition as defined above, characterized in that it also comprises one or more other anti-malarial compounds chosen in particular from pyrimethamine, sulfadoxine, quinine, lumefantrine, mefloquine.

A subject of the invention is also the use of a compound of formula (I) defined above, and more particularly of abovementioned formulae (Ia-bis), (Ib), and (Ic), for the preparation of a medicament intended for the treatment of malaria, and more particularly malaria caused by strains of Plasmodium falciparum resistant to chloroquine.

The invention also relates to the products comprising:

-   -   At least one compound of formula (I) defined above, and more         particularly of abovementioned formulae (Ia-bis), (Ib), and         (Ic),     -   And at least one other anti-malarial compound chosen in         particular from those listed above,         as a combined preparation for simultaneous, separate or         sequential use in the treatment of malaria.

The invention also relates to a process for the preparation of compounds of formula (Ia) defined above, characterized in that it comprises the following stages:

-   -   Treatment of artemisinin with a fluoroalkylating or         fluoroarylating agent as defined above in the scope of the         definition of R₁, such as a trimethylsilane in the presence of         fluoride ions, or an organolithium, which leads to the obtaining         of the compound of the following formula:

In which R₁ is as defined above,

-   -   Dehydration of the compound obtained in the previous stage, in         particular by treatment with SOCl₂ in pyridine, which leads to         the obtaining of the following compound of formula (I):

In which R₁ is as defined above,

-   -   Treatment of the compound obtained in the previous stage with a         halogen, such as bromine, which leads to the obtaining of the         following compound of formula (Ia):

In which R_(x) represents a halogen atom, and R₁ is as defined above,

-   -   Substitution of the R_(x) halogen by a group, if appropriate         ionisable, allowing solubility in water as defined above, which         leads to the obtaining of a compound of the following formula         (Ia-bis):

In which R₁ and R₂ are as defined above.

The invention also relates to the compounds used as synthesis intermediates within the scope of the abovementioned preparation process, and corresponding to the following formulae:

In which R₁ is as defined above,

In which R_(x) represents a halogen atom, and R₁ is as defined above.

A subject of the invention is also a process for the preparation of compounds of formulae (Ib) and (Ic), characterized in that it comprises the treatment of the compound of following formula:

-   -   With the nucleophile of formula HO—R, in which R is as defined         above, in the case where one wishes to obtain a compound of         formula (Ib) in which R₃ represents OR, or with acetonitrile in         the case where one wishes to obtain a compound of formula (Ib)         in which R₃ represents NH₂, or with NH₂—R₆ in which R₆ is as         defined above, in the case where one wishes to obtain a compound         of formula (Ib) in which R₃ represents —NHR₆, agitation at room         temperature, followed by treatment of the reaction mixture with         an aqueous solution of sodium bicarbonate, drying, in particular         over magnesium sulphate, and solvent evaporation, which leads to         the obtaining of the compound of following formula (Ib):

In which R₃ is as defined above,

-   -   With methyllithium at 78° C. under agitation, then at room         temperature, followed by hydrolysis, which leads to the         obtaining of compound of following formula (Ic):

The invention will be further illustrated using the detailed description of new artemisinin derivatives, and their properties.

I Compounds of Formula (Ia)

The compounds of formula (Ia) are prepared from 10-CF₃ hydroartemisinin, already described by the Inventors (Truong Thi Thanh Nga et al., 1998, mentioned above), which has the following formula:

The latter is dehydrated and the enol ether obtained reacts with Br₂ in order to produce an allylic bromide which is the key intermediate being able to be substituted by various functions.

Preparation of methyl-9, CF₃-10 Hydroartemisinin

Hemiketal (100 mg, 2.8×10⁻⁴ mol) dissolved in pyridine (1 ml) (distilled and stored on KOH) is introduced into a flask under argon. SOCl₂ (1.5 eq, 0.032 ml) is added dropwise at 0° C. The reaction mixture is agitated for 1 hour. A solution of 3N hydrochloric acid HCl is added (5 ml), and extraction is carried out with dichloromethane. The organic solution is washed with a sodium chloride saturated solution and dried over MgSO₄. Olefin is obtained in a mixture with the chlorinated derivative in a 90/10 ratio. Silica gel chromatography (petrol ether/ ethyl acetate: 95/5) leads to pure olefin in the form of white crystals (82 mg, 78%).

¹⁹F NMR δ (ppm) −65.2 (qd, ⁵J_(FH)=2.5 Hz, ⁶J_(FH)=1.5 Hz, 3F, CF₃)

¹H (ppm) 1.01 (d, ³J_(H15-H6), 3H, H₁₅) 1.18 (m, 1H, H_(7ax)), 1.24 (qd, ²J=³J_(H8ax-H7ax)=³J_(H8ax-H8a)=13 Hz, ³J_(H8ax-H7eq)=3 Hz 1H, H_(8ax)), 1.44 (s, 3H, H₁₄ and m, 1H, H_(5a)), 1.45 (m, 1H, H₅), 1.46 (m, 1H, H₆) 1.73 (dq, ²J=13 Hz, ³J_(H7eq-H6ax)=³J_(H7eq-H8eq)=³J_(H7eq-H8ax)=3 Hz, 1H, H_(7eq)), 1.82 (m, 1H, H_(8a)), 1.83 (q, ⁵J_(HF)=2.5 Hz, 3H, H₁₆), 1.95 (m, 1H, H₅), 2.03 (m, 1H, H_(8eq)), 2.05 (ddd, ²J=14.5 Hz, ³J_(H4eq-H5ax)=3 Hz, ³J_(H4eq-H5eq)=4.5 Hz, 1H, H_(4eq)), 2.41 (ddd, ²J=14.5 Hz, ³J_(H4ax-H5ax)=13 Hz, ³J_(H4ax-H5eq)=4 Hz, 1H, H_(4ax)), 5.7 (s, 1H, H₁₂).

¹³C δ (ppm) 15.5 (C₁₆), 20.2 (C₁₅), 24.5 (C₅), 25.7 (C₁₄), 28.9 (C₈), 34.2 (C₇), 36.2 (C₄), 37.7 (C₆), 47.5 (C_(8a)), 50.8 (C_(5a)), 78.5 (C_(12a)), 90.5 (C₁₂), 105.0 (C₃), 112.1 (m, C₉), 135 (m, C₁₀).

MP=118° C. (EP/AcOEt)

[α]_(D)=−42.6° (c=0.54, MeOH)

Elementary analysis C₁₆H₂₃F₃O₄ % Calculated C 57.14 6.89 % Found H 57.46 6.33

Preparation of Allylic Bromide

Olefin (100 mg, 3 10⁻⁴ mol) dissolved in 5 ml of carbon tetrachloride CCl₄ is introduced into a flask under argon at 0° C. A solution of dibromine in carbon tetrachloride (5%, 0.4 ml) is added dropwise. The reaction medium is agitated for approximately 2 hours. After washing with a solution of 38% sodium hydrogen-sulphite and extraction with diethyl ether, the solvent is evaporated, then the residue is purified by chromatography on a silica column (petrol ether/ethyl acetate: 90/10) in order to produce allylic bromide in the form of pale yellow crystals (105 mg, 88%).

¹⁹F δ (ppm) −65.8 (s, 3F, CF₃)

¹H δ (ppm) 0.99 (d, ³J_(H5-H6)=6 Hz, 1H, H₁₅) 1.16 (ddd, ³J_(H7axH7eq)=13.5 Hz, ³J_(H7axH8ax)=11.5 Hz, ³J_(H7axH8eq)=3.5 Hz, 1H, H_(7ax)), 1.3 (qd, ²J=³J_(H8axH7ax)=³J_(H8axH8a)=13.5 Hz, ³J_(H8axH7eq)=3.5 Hz, 1H, H_(8ax)), 1.4 (m, 1H, H₆), 1.41 (s, 1H, H₁₆), 1.5 (m, 2H, H₅ and H_(5a)), 1.72 (dq, ²J=13 Hz, ³J_(H7eqH8ax)=³J_(H7eqH8eq)=³J_(H7eqH6)=3.5 Hz, 1H, H_(7eq)), 1.96 (m, 1H, H₅), 2.04 (ddd, ²J=15 Hz, ³J_(H4eqH5ax)=4.5 Hz, J_(H4eqH5eq)=3 Hz, 1H, H_(4eq)), 2.11 (dtd, ²J=13.5 Hz, ³J_(H8eqH7eq)=³J_(H8eqH7ax)=3.5 Hz, ³JH_(8eq)H_(8a)=4.5 Hz, 1H, H_(8eq)), 2.19 (ddd, ³J_(H8aH8ax)=12.5 Hz, ³J_(H8aH8eq)=4.4H, ⁴J_(CF3H8)=1.5 Hz, 1H, H_(8a)), 2.4 (td, ²J_(H4axH5ax)=³JH_(4ax)H_(5ax)=13.5 Hz, ³J_(H4axH5eq)=4 Hz, 1H, H_(4ax)), 4.0 (dq, ²J_(HaHb)=11 Hz, ⁵J_(HaCF3)=1.5 Hz 1H, H_(a)), 4.28 (dq, ²J=11 Hz, ⁵J_(HbCF3)=1 Hz, 1H, Hb), 5.7 (s, 1H, H₁₂).

¹³C δ (ppm) 20 (C₁₅), 24.2 (C₅), 25.5 (C₁₄), 29. (CH₂Br and C₈), 34 (C₇), 36 (C₄), 37.5 (C6), 44.0 (C_(8a)), 50.5 (C_(5a)), 77(C_(12a)), 91 (C₁₂), 105 (C₃), 112 (C₉), 139 (C₁₀).

MP=119.5° C. (EP/Et₂O).

Elementary analysis C₁₆H₂₂O₄F₃Br % Calculated C, 46.28 H, 5.34 % Found C, 46.17 H, 5.10

Substitution by Piperazine Ethanol

Allylic bromide (100 mg, 2.4 10⁻⁴ mol) in 8 ml of THF is introduced into a flask under argon and at 0° C., then piperazine ethanol is added dropwise (126 mg, 2 eq). The mixture is agitated whilst allowing the temperature to rise. The evolution of the reaction is followed by CCM. After 5 hours, the medium is taken up with a sodium chloride saturated solution. The aqueous phase is extracted with Et₂O (3×10 ml), then the organic phase is dried over MgSO₄ and the compound (110 mg) is obtained in the form of light brown crystals with a yield of 98% and with >95% purity. The compound is recrystallized in a petrol ether/AcOEt mixture.

NMR ¹⁹F δ (ppm) −63.1 (s, 3F, CF₃)

¹H δ (ppm) 0.97 (d, ³J_(H15H6)=5.5 Hz, 3H, H₁₅), 1.4 (s, 3H, H₁₄), 1.98 (td, ³J_(H4axH5ax)=²J=13.5 Hz, ³J_(H4axH5eq)=3.5 Hz, 1H, H_(4ax)), 2.51 (m, 8H), 2.84 (s br, 1HOH), 3.05 (s br, 2H), 3.58 (t, ³J_(H22H21)=5.5 Hz, 2H, H₂₂), 5.69 (s, 1H, H₁₂).

¹³C δ (ppm) 20.1 (C₁₅); 24.4 (C₅); 25.5 (C₁₄); 28.7 (C₈); 33.9 (C₇); 36.0 (C₄); 37.5 (C₆); 42.0 (C_(8a)); 42.9 (C16), 50.3 (C_(5a)); 52.5, 54.1, 57.7, 59.2, 77.9 (C_(12a)); 90.8 (C₁₂); 104.9 (C₃); 113.5 (C₉); 138 (C₁₀), CF₃ not observed.

Melting point (EP/AcOEt)=126° C.

Elementary analysis C₂₂H₃₅O₅F₃N₂ % Calculated C, 56.88 H, 7.59 N, 6.03 % Found C, 56.08 H, 7.21 N, 5.27 Hydrochloride: Melting point: 158° C. Solubility in water greater than 50 mg/ml

NMR ¹⁹F δ (ppm) −63.1 (s, 3F, CF₃)

Substitution by Morpholine

Morpholine (126 mg, 2 eq) is added dropwise, under argon, at 0° C., to a solution of allylic bromide (500 mg, 0.1 mmol) in THF (50 mL). The reaction mixture is agitated whilst allowing the temperature to rise. The evolution of the reaction is followed by CCM. After 7 hours, the reaction medium is hydrolysed with a NaCl saturated solution. After extraction with Et₂O (3×20 mL), the organic phase is then dried over MgSO₄. After evaporation of the solvent, the compound is purified by silica gel chromatography (EP/AcOEt:30/70) so as to produce an orange brown solid with morpholine (400 mg, 79%).

¹⁹F δ (ppm) −63.0 (s, 3F, CF₃)

¹H δ (ppm) 0.98 (d, ³J_(H15-H6)=5.5 Hz, 3H, CH₃-15), 1.4 (s, 3H, CH₃-14), 2.3 (m, 2H), 2.5 (m, 6H), 3.04 (m, ³J_(Ha-Hb)=13.5 Hz, ⁵J_(CH2-CF3)=2 Hz, 2H), 3.65 (m, 4H), 5.7 (s, 1H, H-12).

¹³C δ (ppm) 20.0 (C-15), 24.3 (C-5), 25.4 (C-14), 28.6 (C-8), 33.9 (C7), 37.5 (C-4 and C-6), 41.9 (C-8a), 42.9 (C-16), 53.0, 54.4, 67.1, 50.3 (C-5a), 77.8 (C-12a), 90.8 (C-12), 104.8 (C-3), 113.1 (C-9), 137.6 (q, ²J_(C-F)=34 Hz, C-10), CF₃ not observed.

[α]³³ _(D)=+67.4 (c=0.9, MeOH).

Elementary analysis C₂₀H₃₀O₅F₃N % Calculated C, 56.99 H, 7.17 N, 3.32 % Found C, 55.42 H, 6.72 N, 3.09 Hydrochloride: Melting point: 110° C. Solubility in water greater than 20 mg/ml

¹⁹F δ (ppm) −63.0 (s, 3F, CF₃)

Substitution by Ethylamine

A solution of 2 M ethylamine (0.36 mL, 3 eq) in THF is added slowly at 0° C. to a solution of allylic bromide (100 mg, 0.25 mmol) in THF (5 mL). The mixture is agitated whilst allowing the temperature to rise. The evolution of the reaction is followed by CCM. The solution is agitated for 8 hours then hydrolyzed with a sodium chloride saturated solution. After extraction in Et₂O (4×5 mL), the organic phase is dried over MgSO₄. After evaporation of the solvent, the compound is purified by silica gel chromatography (EP/AcOEt:50/50) so as to produce a yellow oil (64 mg, 68%).

¹⁹F δ (ppm) −63.2 (s, 3F, CF₃)

¹H δ (ppm) 0.97 (d, ³J_(H15-H6)=5.5 Hz, 3H, CH₃-15), 1.1 (t, ³J_(CH3-CH2)=7 Hz, 3H, CH₃), 1.4 (s, 3H, CH₃-14), 2.3 (m, 2H), 3.25 (d, ²J_(Ha-Hb)=13.5 Hz, 1H, Ha), 3.5 (d, ²J_(a)=13.5 Hz, Hb), 5.7 (s, 1H, H-12).

¹³C δ (ppm) 14.5 (C-18), 20.0 (C-15), 24.3 (C-5), 25.5 (C-14), 28.9 (C-8), 33.8 (C-7), 36 (C-4), 37.5 (C-6), 42.5 (C-16), 42.6 (C-8a), 43.0, 50.2 (C-5a), 77.8 (C-12a), 90.9 (C-12), 105.0 (C-3), 114.2 (C-9), C-10 and CF₃ not observed.

[α]³³ _(D)=+55.60 (c=0.9, MeOH).

Elementary analysis C₁₈H₂₈O₄F₃N: % Theoretical C, 56.98 H, 7.43 N, 3.69 % Experimental C, 55.25 H, 6.81 N, 2.99

¹⁹F δ (ppm) −63.1 (s, 3F, CF₃)

Substitution by Ethanol FC 487

Allylic bromide (100 mg, 1 eq, 0.24 mmol) and 10% (4 mg) of KI are added at 0° C. to a solution of sodium ethylate in THF prepared under argon from ethanol (0.03 ml, 2 eq, 0.5 mmol) and NaH (2 eq, 20 mg) in 10 ml of THF. The mixture is agitated for approximately 17 hours at ambient temperature then hydrolysed with a NaCl saturated solution. After extraction with Et₂O, the organic phase is dried over MgSO₄. After evaporation of the solvent, the residue is purified by rapid filtration on silica gel (EP/AcOEt: 95/5) in order to produce a white solid (85 mg, 95%).

¹⁹F δ (ppm) −64.06 ppm (s, 3F, CF₃)

¹H δ (ppm) 0.98 (d, ³J_(H15-H6)=5.5 Hz, 3H, CH₃-15), 1.18 (t, ³J_(CH3-CH2)=7 Hz, 3H, CH₃), 1.4 (s, 3H, CH₃-14), 3.3 (qd, ³J_(Ha-CH3)=7 Hz, ²J_(Ha-Hb)=9 Hz, 1H, Ha), 3.5 (qd, ³J_(Hb-CH3)=7 Hz, ²J=9 Hz, 1H, Hb), 4.1 (s, 2H, CH₂), 5.7 (s, 1H, H-12).

¹³C δ (ppm) 15.1 (CH₃), 20.2 (C-15), 24.4 (C-5), 25.5 (C-14), 28.9 (C-8), 9 (C-7), 35.9 (C-4), 37.5 (C-6), 42.2 (C-8a), 50.4 (C-5a), 64.3 (OCH₂), 65.0 (C-16), 77.7 (C-12a), 90.9 (C-12), 104.9 (C-3), 113.1 (C-9), CF₃ and C-10 not observed.

Melting point (EP/Et₂O)=52° C.

α³³ _(D)=+103.5° (c=0.8, MeOH).

Elementary analysis C₁₈H₂₇O₅F₃ % Calculated C, 56.83 H, 7.15 % Found C, 56.97 H, 6.98

Substitution by Methyl Malonate

Methyl malonate (0.36 ml, 1.5 eq, 3 mmol) and NaH (3 eq, 140 mg) are placed under argon in 8 ml of THF at 0° C. Allylic bromide (800 mg, 1 eq, 1.9 mmol) is then added. The mixture is agitated for 4 hours 30 minutes at ambient temperature then hydrolysed with an NaCl saturated solution. The aqueous phase is extracted with Et₂O, then the organic phase is dried over MgSO₄. After evaporation of the solvent, the compound is purified by silica gel chromatography (EP/AcOEt:90/10) in order to produce a white solid (810 mg) with a yield of 90%.

¹⁹F δ (ppm) −66.14 ppm (s, 3F, CF₃)

¹H δ (ppm) 0.94 (d, ³J_(H15-H6)=5.5 Hz, 3H, CH₃-15), 1.35 (s, 3H, CH₃-14), 2.5 (ddq, ²J_(Hb-Ha)=14.5 Hz, ³J_(Hb-CH)=6 Hz, ⁵J_(Hb-CF3)=2 Hz 1H, Hb), 3.0 (ddq, ²J_(Ha-Hb)=14.5 Hz, ³J_(Ha-CH)=6 Hz, ⁵J_(Ha-CF3)=1.5 Hz, 1H, Ha), 3.5 (dd, ³J_(CH-Ha)=³J_(CH-Hb)=6 Hz, 1H, CH), 3.7 (s, 3H, CH₃), 3.71 (s, 3H, CH₃), 5.6 (s, 1H, H-12).

¹³C δ (ppm) 19.9 (C-15), 25.4 (CH₂), 25.5 (C-14), 28.7 (C-8), 33.9 (C-7), 35.9 (C-4), 37.5 (C-6), 42.1 (C-8a), 45.1 (CH), 50.2 (C-5a), 77.7 (C-12a), 90.5 (C-12), 104.8 (C-3), 112.3 (C-9), 136.8 (C-10), 168.9 (CO), 169.5 (CO), CF₃ not observed.

Melting point (EP/Et₂O)=84° C.

α²⁶ _(D)=+70.7° (c=0.9, MeOH).

Elementary analysis C₂₁H₂₉O₈F₃ % Calculated C, 54.43 H, 6.31 % Found C, 53.90 H, 5.88

Hydrolysis to Diacid

A solution of lithium hydroxide (17 mg, 3.3 eq, 0.7 mmol) in 1 mL of water is added to a solution of diester (100 mg, 0.2 mmol) in 1 mL of acetonitrile. The mixture is agitated for 5 hours at ambient temperature, then acidified with a solution of HCl until an acid pH is obtained. After extraction with an Et₂O/AcOEt mixture (2:1) and washing with a NaCl saturated solution, the organic phase is dried over MgSO₄. After evaporation of the solvent, the compound is purified by silica gel chromatography (EP/AcOEt: 30/70) in order to produce a slightly ecru foam (40 mg) with a yield of 40% (this diacid contains 8% of diester, it has not been purified).

¹⁹F δ (ppm) −66.8 ppm (s, 3F, CF₃)

¹H δ (ppm) 0.97 (d, ³J_(H15-H6)=4.5 Hz, 3H, H-15), 1.24 (s, 3H, H-14), 2.1 (ddq, ²J_(Hb-Ha)=15.5 Hz, ³J_(Hb-CH)=7 Hz, ⁵J_(Hb-CF3)=1 Hz 1H, Hb), 3.0 (ddq, ²J_(Ha-Hb)=15.5 Hz, ³J_(Ha-CH)=7 Hz, ⁵J_(Hb-CF3)=1 Hz, 1H, Ha), 3.5 (m ³J_(CH-Ha)=³J_(CH-Hb)=6.5 Hz, 1H), 5.7 (s, 1H, H-12), 8.8 (s br, 2H, COOH).

¹³C δ (ppm) 19.8 (C-15), 24.2 (C-16), 25.3 (C-14), 28.7 (C-8), 33.8 (C-7), 35.8 (C-4), 37.5 (C-6), 45.3 (C-8a), 50.1 (C-17), 51.2 (C-5a), 77.5 (C-12a), 90.5 (C-12), 105 (C-3), 112 (C-9), 120.1 (q, ¹J=278, CF₃), 137.5 (q, ²J=34.5, C-10), 173 (CO), 173.1 (CO), 120.1 (CF₃).

Substitution by Ethanethiol

Ethanethiol (0.02 ml, 1.2 eq, 0.3 mmol) and NaH (1.2 eq, 12 mg) are placed, under argon in 10 ml of THF. Allylic bromide (100 mg, 1 eq, 0.24 mmol) is added to the mixture. The reaction medium is agitated for 1 hour 30 minutes at ambient temperature then hydrolysed with a NaCl saturated solution. The aqueous phase is extracted with Et₂O then the organic phase is dried over MgSO₄. After evaporation of the solvent, the compound is purified by silica gel chromatography (EP/AcOEt: 95/5) in order to produce a colourless oil (30 mg) with a yield of 31%.

¹⁹F δ (ppm) −64.14 ppm (s, 3F, CF₃)

¹H δ (ppm) 0.99 (d, ³J_(H15-H6)=6.5 Hz, 3H, CH₃-15), 1.1 (m, 1H, H-7), 1.22 (t, ³J_(CH3-CH2)=7.3 Hz, 3H, CH₃), 1.3 (m, 1H, H-8), 1.41 (s, 3H, CH₃-14), 1.5 (m, 1H, H-6), 1.55 (m, 1H, H-5a), 1.7 (dq, ²J=13 Hz, ³J_(H7′-H8′)=³J_(H7′-H8′)=³J_(H7′-H6)=3 Hz, 1H, H-7′), 1.95 (m, 1H, H-5′), 2.0 (m, 1H, H-8′), 2.05 (m, 1H, H-4′), 2.4 (m, 1H, H-4), 2.49 (q, ³J_(CH2-CH3)=7 Hz, 2H, CH₂), 2.53 (dd, ³J_(H8a-H8)=7 Hz, ³J_(H8a-H8′)=5 Hz, 1H, H-8a), 2.98 (dq, ²J=14.5 Hz, ⁵J_(Ha-CF3)=2 Hz, 1H, Ha), 3.74 (dq, ²J=14.5 Hz, ⁵J_(Hb-CF3)=1 Hz, 1H, Hb), 5.7 (s, 1H, H-12).

¹³C δ (ppm) 14.2 (CH₃), 20.0 (C-15), 24.2 (C-5), 24.3 (CH₂), 25.5 (C-14), 28.7 (C-8), 29.12 (q, J=3 Hz, CH₂—S), 33.9 (C-7), 35.9 (C-4), 37.5 (C-6), 42.5 (C-8a), 50.2 (C-5a), 77.6 (C-12a), 90.8 (C-12), 104.9 (C3), 112.5 (J=2 Hz, C-9), 120.5 (q, J=275 Hz, CF₃), 136.9 (q, J=34 Hz, C-10).

[α]³³ _(D)=+33.6° (c=1.1, MeOH)

II Compounds of Formulae (Ib) and (Ic)

The C-10 brominated starting compound is described in Organic Letters 2002, 4 (5), 757-759.

RMN (CDCl₃): δ (ppm)

¹H 0.98 (qd, ²J_(H7ax-H7eq)=³J_(H7ax-H8ax)=³J_(H7ax-H6)=13.5 Hz, ³J_(H7ax-H8eq)=3.5 Hz, 1H, H-7ax), 1.0 (d, ³J_(H15-H6)=6 Hz, 3H, CH₃-15), 1.15 (d, ³J_(H16-H9)=7Hz, 3H, CH₃-16), 1.35 (td, ³J_(H5a-H5ax)=³J_(H5a-H6)=11 Hz, ³J_(H5a-H5eq)=6.5 Hz, 1H, H-5a), 1.42 (m, 1H, H-6), 1.43 (s, 3H, CH₃-14), 1.55 (tdd, ²J_(H5ax-H5eq)=³J_(H5ax-H4ax)=13.5 Hz, ³J_(H5ax-H4eq)=5 Hz, ³J_(H5ax-H5a)=11 Hz, 1H, H-5ax), 1.68 (td, ³J_(H8a-H9)=³J_(H8a-H8eq)=4.5 Hz, ³J_(H8a-H8ax)=14 Hz, 1H, H-8a), 1.78 (dq, ²J_(H7eq-H7ax)=13 Hz, ³J_(H7eq-H8ax)=³J_(H7eq-H8eq)=³J_(H7eq-H6)=3.5 Hz, 1H, H-7eq), 1.86 (dq, ²J_(H8eq-H8ax)=14 Hz, ³J_(H8eq-H7ax)=³J_(H8eq-H7eq)=³J_(H8eq-H8a)=3.5 Hz, 1H, H-8eq), 1.95 (dddd, ²J_(H5eq-H5ax)=14 Hz, ³J_(H5eq-H5a)=6 Hz, ³J_(H5eq-H4ax)=4 Hz, ³J_(H5eq-H4eq)=3 Hz, 1H, H-5eq), 2.1 (ddd, ²J_(H4eq-H4ax)=14.5 Hz, ³J_(H4eq-H5ax)=5 Hz, ³J_(H4eq-H5eq)=3 Hz, 1H, H-4eq), 2.29 (qd, ²J_(H8ax-H8eq)=³J_(H8ax-H7ax)=³J_(H8ax-H8a)=14 Hz, ³J_(H8ax-H7eq)=3.5 Hz, 1H, H-8ax), 2.4 (td, ²J_(H4ax-H4eq)=³J_(H4ax-H5ax)=14 Hz, ³J_(H4ax-H5eq)=4 Hz, 1H, H-4ax), 2.95 (qd, ³J_(H9-H16)=7 Hz, ³J_(H9-H8a)=5.5 Hz, 1H, H-9), 5.55 (s, 1H, H-12)

¹³C 15.6 (C-16), 20.5 (C-15), 23 (C-8), 25 (C-5), 26 (C-14), 33.2 (C-9), 34.9 (C-7), 36.2 (C-4), 37.8 (C-6), 47 (C-8a), 52.7 (C-5a), 80 (C-12a), 92 (C-12), 101 (C-10), 106 (C-3), CF₃ not observed.

¹⁹F −77.9 (s, 3F, CF₃)

Elementary analysis for C₁₆H₂₂F₃O₄ (415.25 g.mol⁻¹) % Calculated C 46.30% H 5.34% % Found C 46.24% H 5.37%

T_(Melting)=116° C.

[α]_(D)=+182 (0.9; MeOH)

General Operating Mode:

The C-10 brominated compound (415 mg; 1 mmol) is dissolved in dichloromethane (5 mL). Hexafluoroisopropanol (520 μL; 5 mmol) and then the nucleophile (10 mmol) are added to this solution. The reaction mixture is treated with an aqueous solution of sodium bicarbonate after 12 hours agitation at room temperature, it is dried over magnesium sulphate, and the solvent is evaporated. The product is then obtained by silica gel purification.

Substitution by Methanol

This compound is synthesised according to the general operating mode. After purification on silica gel (petrol ether/ethyl acetate 9/1) 238 mg (65%) of white crystals are obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.92 (1H₇); 0.95 (3H₁₅; d; J₁₅₋₆=6.2 Hz); 0.98 (3H₁₆; dq; J₁₆₋₉=7.2 Hz; J_(16-F)=1.2 Hz); 1.25 (1H_(5a)); 1.3 (2H₆); 1.42 (3H₁₄; s); 1.5 (1H₈a); 1.5 (1H₅); 1.65 (H₇); 1.65 (1H₈); 1.78 (1H₈); 1.9 (H₅); 2.03 (H_(4eq); ddd; J_(4eq-4ax)=14.6 Hz; J_(4eq-5ax)=3.0 Hz; J_(4eq-5eq)=5.1 Hz); 2.37 (H_(4ax); ddd; J_(4ax-4eq)=14.6 Hz; J_(4ax-5a)=13.4 Hz; J_(4ax-5eq)=4.1 Hz); 2.83 (H9; dq; J₉₋₁₆=7.2 Hz; J_(9-8a)=4.9); 3.43 (3H₁₇; q; J_(17-CF3)=1.8 Hz); 5.3 (H₁₂, s)

¹³C 11.9 (C₁₆); 20.0 (C₁₅); 23.4 (C₈); 24.6 (C₅); 25.6 (C₁₄); 29.5 (C₉); 34.5 (C₇); 36.1 (C₄); 37.4 (C₆); 46.0 (C_(8a)); 49.9 (C₁₇); 52.0 (C_(5a)); 79.8 (C_(12a)); 89.1 (C₁₂); 98.6 (C₁₀; q; ²J_(C-F)=29 Hz); 104.3 (C₃); 122.5 (CF₃; q; ¹J_(C-F)=293 Hz)

¹⁹F −75.5 (s, 3F, CF₃)

Elementary analysis for C₁₇H₂₅F₃O₅ (366.38 g · mol⁻¹) % Calculated C 55.73% H 6.88% % Found C 55.62% H 6.79%

T_(Melting)=82° C.

[α]_(D)=+135.6 (0.45; MeOH)

Substitution by Ethanol

This compound is synthesised according to the general operating mode. After purification on silica gel (petrol ether/ethyl acetate 9/1) 266 mg (70%) of white crystals are obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.91 (3H₁₅; d; J₁₅₋₆=5.5 Hz); 0.96 (3H₁₆; d; J₁₆₋₉=7.0 Hz); 1.15 (3H₁₈; t; J₁₈₋₁₇=7.1 Hz); 1.35 (3H₁₄; s); 2.31 (1H₄; m); 2.76 (H₉; m); 3.61 (1H₁₇; m); 3.84 (1H₁₇; m); 5.27 (1H₁₂; s)

¹³C 11.9 (C₁₆); 15.1 (C₁₈); 19.9 (C₁₅); 23.3 (C₈); 24.5 (C₅); 25.5 (C₁₄); 29.5 (C₉); 34.5 (C₇); 36.0 (C₄); 37.4 (C₆); 46.0 (C_(8a)); 50.0 (C_(5a)); 58.2 (C₁₇); 79.8 (C_(12a)); 89.0 (C₁₂); 98.4 (C₁₀; q; ²J_(C-F)=29 Hz); 104.2 (C₃); 122.4 (CF₃; q; ¹J_(C-F)=293 Hz)

¹⁹F −75.7 (s, 3F, CF₃)

Elementary analysis for C₁₈H₂₇F₃O₅ (380.41 g · mol⁻¹) % Calculated C 56.83% H 7.15% % Found C 56.72% H 7.23%

T_(Melting)=94° C.

[α]_(D)=+106.7 (0.52; MeOH)

Substitution by Trifluoroethanol

The C-10 brominated compound (1.3 g; 3.1 mmol) is dissolved in trifluoroethanol (5 mL), then triethylamine (316 mg; 3.1 mmol) is added to this solution. The reaction mixture is diluted in ether after 12 hours agitation at room temperature, then the organic phase is washed with an aqueous solution of sodium bicarbonate, dried over magnesium sulphate, and the solvent is evaporated. After silica gel purification (petrol ether/ethyl acetate 95/5) 458 mg (34%) of white crystals are obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.90 (1H_(7ax)); 0.96 (3H₁₅; d; J₁₅₋₆=5.9 Hz); 1.04 (3H₁₆; dq; J₁₆₋₉=7.2 Hz; J_(16-CF3)=0.9 Hz); 1.30 (1H₆); 1.40 (1H₅); 1.42 (3H₁₄; s); 1.55 (1H_(8a)); 1.63 (H₈); 1.69 (1H_(7eq); dq; J_(7eq-7ax)=12.9; J_(7eq-6)=J_(7eq-8ax)=J_(7eq-8eq)=3.4 Hz); 1.82 (1H₈); 1.90 (H₅); 2.04 (1H_(4eq); ddd; J_(4eq-4ax)=14.6 Hz; J_(4eq-5ax)=4.5 Hz; J_(4eq-5eq)=5.0 Hz); 2.38 (1H_(4ax); ddd; J_(4ax-4eq)=14.6 Hz; J_(4ax-5ax)=13.6 Hz; J_(4ax-5eq)=4.0 Hz); 2.92 (1H₉; m); 3.90 (1H₁₇; qd; J_(17-CF3)=8.5 Hz; J₁₇₋₁₇=8.5 Hz); 4.35 (1H₁₇; qd; J_(17-CF3)=8.5 Hz; J₁₇₋₁₇=8.5 Hz); 5.4 (1H₁₂, s)

¹³C 12.0 (C₁₆); 20.2 (C₁₅); 22.9 (C₈); 24.7 (C₅); 25.7 (C₁₄); 29.3 (C₉); 34.7 (C₇); 36.2 (C₄); 37.6 (C₆); 45.7 (C₈a); 52.1 (C_(5a)); 60.3 (C₁₇; q; ¹J_(C-F)=36 Hz); 79.9 (C_(12a)); 89.4 (C₁₂); 99.0 (C₁₀; q; ²J_(C-F)=30 Hz); 104.8 (C₃); (CF₃; q; ¹J_(C-F)=291 Hz); (CF₃; q; ¹J_(C-F)=277 Hz)

¹⁹F −74.3 (3F; t; ¹J_(F-H)=8.5 Hz); −75.9 (s, 3F, CF₃)

Elementary analysis for C₁₈H₂₄F₆O₅ (434.38 g · mol⁻¹) % Calculated C 49.77% H 5.57% % Found C 49.81% H 5.61%

T_(Melting)=104° C.

[α]_(D)=+97.5 (0.44; MeOH)

Substitution by Ethylene Glycol

The C-10 brominated compound (1.939 g; 4.7 mmol) is dissolved in a 1/1 mixture of THF and ethylene glycol (8 mL), then triethylamine (472 mg; 4.7 mmol) is added to this solution. The reaction mixture is diluted by ether after 12 hours agitation at room temperature, then the organic phase is washed with an aqueous solution of sodium chloride, dried over magnesium sulphate, and the solvent is evaporated. After silica gel purification (petrol ether/ethyl acetate 9/1) 637 mg (37%) of pale yellow crystals are obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.95 (3H₁₅; d; J₁₅₋₆=5.8 Hz); 1.01 (3H₁₆; d; J₁₆₋₉=7.3 Hz); 1.42 (3H₁₄; s); 2.37 (1H₄; m); 2.86 (H₉; m); 3.75 (3H; m); 3.98 (1H); 5.5 (H₁₂)

¹³C 12.0 (C₁₆); 20.1 (C₁₅); 23.1 (C₈); 24.6 (C₅); 25.6 (C₁₄); 29.6 (C₉); 34.6 (C₇); 36.2 (C₄); 37.3 (C₆); 46.0 (C_(8a)); 52.1 (C_(5a)); 61.6 (C_(17 ou 18)); 64.4 (C_(17 ou 18)); 80.1 (C_(12a)); 89.1 (C₁₂); 98.6 (C₁₀; q; ²J_(C-F)=29 Hz); 104.4 (C₃); 122.5 (CF₃; q; ¹J_(C-F)=293 Hz)

¹⁹F −76.0 (s, 3F, CF₃)

Elementary analysis for C₁₈H₂₇F₃O6 (396.41 g · mol⁻¹) % Calculated C 54.54% H 6.87% % Found C 54.51    H 6.87   

T_(Melting)=92° C.

[α]_(D)=+109.6 (0.44; MeOH)

Substitution by Acetonitrile

The C-10 brominated compound (538 g; 1.3 mmol) is dissolved in acetonitrile (10 mL), then succinic acid (3 g; 26 mmol) and triethylamine (655 mg; 6.5 mmol) are added to this solution. After two days agitation at room temperature, the reaction mixture is diluted with ethyl acetate and the organic phase is washed with an aqueous solution of sodium chloride, it is dried over magnesium sulphate, and the solvent is evaporated. After silica gel purification (petrol ether/ethyl acetate 5/5) 114 mg (25%) of white crystals are obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.89 (3H15; d; J15-6=4.3 Hz); 1.02 (3H16; d; J16-9=7.4 Hz); 1.34 (3H14; s); 2.93 (H9; m); 5.37 (NH; s large); 5.69 (H12; s broad)

¹³C 12.3 (C₁₆); 19.9 (C₁₅); 22.9 (C₈); 24.4 (C₅); 25.5 (C₁₄); 29.6 (C₉); 34.3 (C₇); 36.0 (C₄); 37.2 (C₆); 45.9 (C₈a); 51.9 (C₅a); 79.4 (C_(12a)); 89.2 (C₁₂); 98.6 (C₁₀; q; ²J_(C-F)=29 Hz); 104.5 (C₃); 123.1 (CF₃; q; ¹J_(C-F)=Hz)

¹⁹F −79.6 (s, 3F, CF₃)

Elementary analysis for C₁₆H₂₄F₃NO₄ (351.37 g · mol⁻¹) % Calculated C 54.69% H 6.88% N 3.99% % Found C 53.30% H 6.52% N 3.02%

T_(Melting)=145° C.

[α]_(D)=+134.8 (0.18; MeOH)

Substitution by Succinic Acid

The C-10 brominated compound (456 g; 1.1 mmol) is dissolved in a 1/1 mixture of dichloromethane and hexafluoroisopropanol (8 mL), then succinic acid (1.3 g; 11 mmol) and triethylamine (555 mg; 5.5 mmol) are added to this solution. After 12 hours agitation at room temperature, the reaction mixture is diluted with ethyl acetate, then the organic phase is washed with an aqueous solution of sodium chloride, drying is performed over magnesium sulphate, and solvent is evaporated. After silica gel purification (petrol ether/ethyle acetate 8/2 then AcOEt alone) 328 mg (66%) of a beige foam is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.94 (3H15; d; J15-6=5.5 Hz); 1.05 (3H16; d; J16-9=6.9 Hz); 1.40 (3H14; s); 2.34 (1H4; m); 2.62 (2H18 et 2H19; m); 2.88 (H9; m); 5.54 (H12; s); 8.39 (COOH; s broad)

¹³C 11.95 (C₁₆); 20.0 (C₁₅); 23.0 (C₈); 24.3 (C₅); 25.5 (C₁₄); 28.5 (C₁₈; m); 29.9 (C₁₉); 30.1 (C₉); 34.4 (C₇); 36.0 (C₄); 37.1 (C₆); 45.6 (C_(8a)); 51.8 (C_(5a)); 79.5 (C_(12a)); 90.4 (C₁₂); 102.1 (C₁₀; q; ²J_(C-F)=32 Hz); 104.7 (C₃); 121.5 (CF₃; q; ¹J_(C-F)=289 Hz); 168.5 (C₁₇); 177.4 (C₂₀)

¹⁹F −77.2 (s, 3F, CF₃)

Elementary analysis for C₂₀H₂₇F₃O₈ (452.43 g · mol⁻¹) % Calculated C 53.10% H 6.02% % Found C 52.49% H 6.04%

Substitution by Anisidine

This compound is synthesised according to the general operating mode. After silica gel purification (petrol ether/ethyl acetate 9/1) 114 mg (25%) of an orange foam is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.95 (3H15; d; J15-6=5.4 Hz); 1.11 (3H16; d; J16-9=7.3 Hz); 1.47 (3H14; s); 2.39 (1H4; m); 3.05 (H9; m); 3.63 (NH; s broad); 3.75 (3H21; s); 5.56 (H12; s); 6.81 (2H_(Ar); m); 7.04 (2H_(Ar); m)

¹³C 12.6 (C₁₆); 20.0 (C₁₅); 23.5 (C₈); 24.5 (C₅); 25.7 (C₁₄); 30.1 (C₉); 34.3 (C₇); 36.2 (C₄); 37.2 (C₆); 46.3 (C_(8a)a); 52.2 (C_(5a)); 55.2 (C₂₁); 80.1 (C_(12a)); 88.3 (C₁₀; q; ²J_(C-F)=28 Hz); 90.0 (C₁₂); 104.3 (C₃); 114.2 (C₁₈); 119.2 (C₁₉); 123.8 (CF₃; q; ¹J_(C-F)=294 Hz); 136.4 (C₁₇); 154.0 (C₂₀)

¹⁹F −75.5 (s, 3F, CF₃)

Elementary analysis for C₂₃H₃₀F₃NO₅ (457.49 g · mol⁻¹) % Calculated C 60.38% H 6.61% N 3.06% % Found C 60.22% H 6.65% N 2.97%

[α]_(D)=+93.6 (0.34; MeOH)

Substitution by Allylic Alcohol

This compound is synthesised according to the general operating mode. After silica gel purification (petrol ether/acétate d'éthyle 9/1) 255 mg (65%) of a light yellow oil is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.94 (3H₁₅; d; J₁₅₋₆=5.8 Hz); 1.01 (3H₁₆; dq; J₁₆₋₉=7.2 Hz; ⁵J_(H-F)=1.3 Hz); 1.41 (3H₁₄; s); 2.37 (1H₄; m); 2.85 (H₉); 4.15 (1H₁₇; dm; J₁₇₋₁₇=12.8 Hz); 4.35 (1H₁₇; dd; J₁₇₋₁₇=12.8 Hz; J₁₇₋₁₈=5.8 Hz); 5.15 (1H₁₉; dq; J₁₉₋₁₈=10.3 Hz; J₁₉₋₁₉=J₁₉₋₁₇=1.6 Hz); 5.28 (1H₁₉; dq; J₁₉₋₁₈=17.3 Hz; J₁₉₋₁₉=J₁₉₋₁₇=1.6 Hz); 5.31 (H₁₂; s); 5.89 (H₁₈; m)

¹³C 12.2 (C₁₆); 20.2 (C₁₅); 23.5 (C₈); 24.7 (C₅); 25.8 (C₁₄); 29.7 (C₉); 34.7 (C₇); 36.2 (C₄); 37.6 (C₆); 46.1 (C_(8a)); 52.1 (C_(5a)); 63.9 (C₁₇); 80.1 (C_(12a)); 89.3 (C₁₂); 98.7 (C₁₀; q; ²J_(C-F)=29 Hz); 104.5 (C₃); 116.6 (C₁₉); 122.6 (CF₃; q; ¹J_(C-F)=293 Hz); 134.0 (C₁₈)

¹⁹F −75.9 (s, 3F, CF₃)

Elementary analysis for C₁₉H₂₇F₃O₅ (392.42 g · mol⁻¹) % Calculated C 58.16% H 6.94% % Found C % H %

Fluoride Elimination

The C-10 compound (1.223 g; 2.9 mmol) is dissolved in anhydrous THF (20 mL), then methyl-lithium (3.7 mL; 1.6M; 5.9 mmol) is added at −78° C. under argon. After 2 hours at low temperature agitation is performed 1 more hour at room temperature, then hydrolysis is performed with a saturated ammonium chloride solution. After silica gel purification (petrol ether/ethyle-acetate 9/1) 575 mg (62%) of a pale yellow oil is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.93 (3H₁₅; dm; J₁₅₋₆=5.7 Hz); 1.06 (3H₁₆; t; J₁₆₋₉=⁴J_(H-F)=7.0 Hz); 1.41 (3H₁₄; d; J_(H-F)=1.4 Hz); 2.35 (1H₄; m); 3.23 (H₉; m); 5.3 (H₁₂)

¹³C 12.9 (C₁₆; d; ⁴J_(C-F)=9.4 Hz); 19.9 (C₁₅); 21.9 (C₈); 24.6 (C₅); 25.5 (C₁₄); 28.5 (C₉; d; ³J_(C-F)=3.9 Hz); 33.6 (C₇); 35.8 (C₄); 37.1 (C₆); 46.2 (C_(8a); ⁴J_(C-F)=2.3 Hz); 51.3 (C_(5a)); 80.7 (C_(12a)); 93.6 (C₁₂; dd; ⁴J_(C-F)=2.3 Hz; ⁴J_(C-F)=1.1 Hz); 104.4 (C₃); 114.5 (C₁₀; dd; ²J_(C-F)=35 Hz; ²J_(C-F)=14 Hz); 154.9 (CF₂; dd; ¹J_(C-F)=286 Hz; ¹J_(C-F)=282 Hz)

¹⁹F −117.0 (1F; dm; ¹J_(F-F)=80 Hz); −98.9 (1F; dm; ¹J_(F-F)=80 Hz)

Elementary analysis for C₁₆H₂₂F₂O₄ (316.35 g · mol⁻¹) % Calculated C 60.75% H 7.01% % Found C 60.12% H 7.10%

Oxidation to Acid

The abovementioned allylic compound (595 mg; 1.5 mmol) is dissolved in a tertiary mixture of carbon tetrachloride (3 mL), acetonitrile (3 mL) and water (5 mL). Sodium periodate (1.6 g; 7.6 mmol) and ruthenium trichloride (8 mg; 0.03 mmol) are then added to this solution. After one night the reaction mixture is diluted with ethyl acetate and the organic phase is washed with an aqueous solution of sodium bisulfite. After silica gel purification (petrol ether/ethyl acetate 7/3) 299 mg (48%) of a colourless foam is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.91 (3H₁₅; d; J₁₅₋₆=5.7 Hz); 1.00 (3H₁₆; d; J₁₆₋₉=7.1 Hz); 1.37 (3H₁₄; s); 2.30 (1H₄; m); 2.84 (H₉; m); 4.18 (1H₁₇; d; J₁₇₋₁₇=16.4 Hz); 4.62 (1H₁₇; d; J₁₇₋₁₇=16.4 Hz); 5.44 (H₁₂; s); 8.55 (COOH broad)

¹³C 12.1 (C₁₆); 20.2 (C₁₅); 22.8 (C₈); 24.7 (C₅); 25.7 (C₁₄); 29.5 (C₉); 34.7 (C₇); 36.2 (C₄); 37.3 (C₆); 45.9 (C_(8a)); 52.1 (C_(5a)); 60.7 (C₁₇); 80.2 (C_(12a)); 89.6 (C₁₂); 98.9 (C₁₀; q; ²J_(C-F)=29 Hz); 104.7 (C₃); 122.4 (CF₃; q; ¹J_(C-F)=292 Hz); 175.5 (C₁₈)

¹⁹F −76.1 (s, 3F, CF₃)

Elementary analysis for C₁₈H₂₅F₃O₇ (410.39 g · mol⁻¹) % Calculated C 52.68% H 6.14% % Found C 52.75% H 6.31%

[α]_(D)=+71.2 (0.80; MeOH)

IR: ν (cm⁻¹) 1728 (CO); 3200 broad (COOH)

Oxidation to Aldehyde

This compound is obtained as an intermediate product of the latter reaction. Thus, operating conditions have not been optimised to obtain it as a unique compound.

RMN (CDCl₃): δ (ppm)

¹H 0.94 (3H₁₅; d; J₁₅₋₆=5.5 Hz); 1.04 (3H₁₆; d; J₁₆₋₉=7.1 Hz); 1.39 (3H₁₄; s); 2.35 (1H₄; m); 2.88 (H₉; m); 4.35 (1H₁₇; dm; J₁₇₋₁₇=18.4 Hz); 4.54 (1H₁₇; d; J₁₇₋₁₇=18.4 Hz); 5.28 (H₁₂; s); 9.6 (H₁₈)

¹³C 12.0 (C₁₆); 20.1 (C₁₅); 23.1 (C₈); 24.5 (C₅); 25.6 (C₁₄); 29.4 (C₉); 34.5 (C₇); 36.0 (C₄); 37.3 (C₆); 45.6 (C_(8a)); 51.8 (C_(5a)); 68.4 (C₁₇); 79.9 (C_(12a)); 89.4 (C₁₂); 98.8 (C₁₀; q; ²J_(C-F)=29 Hz); 104.6 (C₃); 122.2 (CF₃; q; ¹J_(C-F)=292 Hz); 197.8 (C₁₈)

¹⁹F −76.3 (s, 3F, CF₃)

Elementary analysis for C₁₈H₂₅F₃O₆ (394.39 g · mol⁻¹) % Calculated C 54.82% H 6.39% % Found C 54.71% H 6.47%

[α]_(D)=+94.0 (0.32; MeOH)

Substitution by HPU (Hydrogen Peroxide Urea)

The C-10 brominated compound (92 mg; 0.22 mmol) is dissolved in dichloromethane (2 mL). A solution of the hydrogen peroxide-urea complex (208 mg; 2.2 mmol) is then added to it in hexafluoroisopropanol (2 mL). After 12 hours agitation at room temperature excess HPU is precipitated by adding diethylic ether, then filtration over silica is performed. The solvent is then cautiously evaporated. After silica gel purification (petrol ether/ethyl acetate 9/1) 59 mg (73%) of white crystals is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.90 (3H₁₅; d; J₁₅₋₆=Hz); 0.94 (3H₁₆; d; J₁₆₋₉=8.0 Hz); 1.38 (3H₁₄; s); 2.32 (1H₄; m); 2.95 (H₉; m); 5.53 (H₁₂; s); 8.83 (OH; s)

¹³C 11.6 (C₁₆); 20.0 (C₁₅); 24.0 (C₈); 24.6 (C₅); 25.6 (C₁₄); 30.1 (C₉); 34.3 (C₇); 36.1 (C₄); 37.4 (C₆); 45.4 (C_(8a)); 51.9 (C_(5a)); 79.9 (C_(12a)); 89.7 (C₁₂); (C₁₀; q; ²J_(C-F)=Hz); 105.0 (C₃); 116.6 (C₁₉); 121.6 (CF₃; q; ¹J_(C-F)=290 Hz)

¹⁹F −74.6 (s, 3F, CF₃)

Elementary analysis for C₁₆H₂₃F₃O₆ (368.35 g · mol⁻¹) % Calculated C 52.17% H 6.29% % Found C 51.28% H 6.66%

Oxidation to Diol

The abovementioned allylic compound (396 mg; 1.0 mmol) is dissolved in a terbutanol (20 mL) water (2 mL) mixture. N-oxide morpholine (150 mg; 1.1 mmol) and osmium tetraoxide (13 mg; 0.05 mmol) are then added to this solution. After 3 hours, the reaction mixture is diluted with ethyl acetate, then the organic phase is washed successively with a sodium bisulfite aqueous solution, a sodium bicarbonate solution, and a sodium chloride solution. After silica gel purification (petrol ether/ethyl acetate 8/2) 257 mg (60%) of a colourless foam is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.94 (3H₁₅; d; J₁₅₋₆=5.8 Hz); 1.00 (3H₁₆; d; J₁₆₋₉=7.3 Hz); 1.41 (3H₁₄; s); 2.37 (1H₄; m); 2.86 (1H₉); 3.41-4.05 (5H; m); 5.48 (H_(12 mino)); 5.55 (H_(12 majo))

¹³C 11.7 (C₁₆); 19.7 (C₁₅); 22.6 (C₈); 22.8 (C₈); 24.3 (C₅); 25.2 (C₁₄); 29.3 (C₉); 34.4 (C₇); 35.8 (C₄); 36.85 (C₆); 36.90 (C₆); 45.6 (C_(8a)); 45.7 (C_(8a)); 51.8 (C_(5a)); 63.3 (C₁₉); 63.5 (C₁₉); 63.6 (C₁₇); 64.2 (C₁₇); 70.6 (C₁₈); 71.0 (C₁₈); 79.7 (C_(12a)); 79.8 (C_(12a)); 88.7 (C₁₂); 88.8 (C₁₂); 98.22 (C₁₀; q; ²J_(C-F)=29 Hz); 98.25 (C₁₀; q; ²J_(C-F)=29 Hz); 104.0 (C₃); 122.2 (CF₃; q; ¹J_(C-F)=293 Hz)

¹⁹F −76.1 (40%); −76.2 (60%)

Elementary analysis for C₁₉H₂₉F₃O₇ (426.43 g · mol⁻¹) % Calculated C 53.52% H 6.85% % Found C 53.81% H 6.58%

Olefin to Diol Oxidation

The abovementioned olefin (100 mg; 0.3 mmol) is dissolved in a carbon tetrachloride (1 mL), acetonitrile (1 mL) and water (1.5 mL) mixture. Sodium periodate (1.5 eq) and then ruthenium trichloride (0.02 eq) are added to this solution. After overnight reaction the reaction mixture is diluted with ethyl acetate, then the organic phase is successively washed with a sodium bisulfite aqueous solution, a sodium bicarbonate solution, and a sodium chloride solution. After silica gel purification (petrol ether/ethyl acetate 9/1) 66 mg (65%) of white crystals are obtained (diastereoisomer mixture 65/35).

RMN (CDCl₃): δ (ppm)

¹H 0.96 (3H₁₅; d; J₁₅₋₆=5.9 Hz); 1.00 (H_(7ax)); 1.30 (1H₆); 1.32 (H_(5a)); 1.36 (3H₁₆; s); 1.44 (3H₁₄; s); 1.50 (1H₈); 1.53 (1H₅); 1.66 (H_(7eq); dq; J_(7eq-7ax)=13.1; J_(7eq-6)=J_(7eq-8ax)=J_(7eq-8eq)=3.3 Hz); 1.76 (H_(8a); dd; J_(8a-8ax)=12.0 Hz; J_(8a-8eq)=5.7 Hz); 1.90 (1H₈); 1.92 (1H₅); 2.08 (H_(4eq); ddd; J_(4eq-4ax)=14.6 Hz; J_(4eq-5ax)=4.8 Hz; J_(4eq-5eq)=3.0 Hz); 2.37 (H_(4ax); ddd; J_(4ax-4eq)=14.6 Hz; J_(4ax-5ax)=13.8 Hz; J_(4ax-5eq)=4.2 Hz); 3.21 (OH₁₀; s); 4.66 (OH₉; s); 5.61 (H₁₂, s)

¹³C 20.2 (C₁₅); 22.6 (C₁₆; q; ⁴J_(C-F)=3.1 Hz); 24.5 (C₈); 25.5 (C₅); 25.6 (C₁₄); 34.3 (C₇); 36.1 (C₄); 37.6 (C₆); 52.0 (C_(5a)); 52.1 (C_(8a); q; 4JC-F=1.6 Hz); 72.1 (C₉; q; 3JC-F=1.2 Hz); 83.0 (C_(12a)); 88.9 (C₁₂); 98.8 (C₁₀; q; ²J_(C-F)=29 Hz); 104.8 (C₃); 116.6 (C₁₉); 122.5 (CF₃; q; ¹J_(C-F)=289 Hz)

¹⁹F −79.3 (s, 3F, CF₃)

Elementary analysis for C₁₆H₂₃F₃O₆ (368.35 g · mol⁻¹) % Calculated C 52.17% H 6.29% % Found C 52.24% H 6.36%

Substitution by Dimethanol Benzene

This compound is synthesised according to the general operating mode with monoacetylated dimethanol benzene as a nucleophile. The corresponding ester is then dissolved in methanol (3 mL) and potassium carbonate (2 eq) is added to it. After silica gel purification (petrol ether/ethyl acetate 9/1) 25% of white crystals is obtained.

RMN (CDCl₃): δ (ppm)

¹H 0.91 (3H₁₅; d; J₁₅₋₆=5.9 Hz); 1.05 (3H₁₆; d; J₁₆₋₉=7.3 Hz); 1.44 (3H₁₄; s); 2.38 (1H₄; m); 2.90 (1H₉; m); 4.69 (2H₁₈; s); 4.72 (1H₁₇; d; J₁₇₋₁₇=11.7 Hz); 4.83 (1H₁₇; d; J₁₇₋₁₇=11.7 Hz); 5.37 (H₁₂; s)

¹³C 12.2 (C₁₆; m); 20.1 (C₁₅); 23.4 (C₈); 24.6 (C₅); 25.8 (C₁₄); 29.7 (C₉); 34.5 (C₇); 36.2 (C₄); 37.5 (C₆); 45.9 (C_(8a)); 52.0 (C_(5a)); 64.7 (C₁₇; q; ⁴J_(C-F)=2.0 Hz); 65.0 (C₁₈); 79.7 (C_(12a)); 80.0 (C_(12a)); 89.4 (C₁₂); 88.8 (C₁₂); 98.9 (C₁₀; q; ²J_(C-F)=29 Hz); 104.6 (C₃); 122.6 (CF₃; q; ¹J_(C-F)=293 Hz); 127.0 (C_(Ar)); 127.7 (C_(Ar)); 136.9 (C_(Ar)); 140.3 (C_(Ar))

¹⁹F −75.4 (s, 3F, CF₃)

Elementary analysis for C₂₄H₃₁F₃O₆ (472.51 g · mol⁻¹) % Calculated C 61.01% H 6.61% % Found C % H %

III Biological activities

The above products have proved to be active on P. Falciparum, equally well on resistant as non-resistant strains, as well as in vivo in the Peters test on mice infected by Plasmodium berghei.

Thus, by way of an example, the compound substituted by piperazine ethanol has nanomolar IC₅₀ values of 17 and of 3 respectively vis-à-vis sensitive and resistant (W2) strains of P. falciparum respectively. The same compound provides the mice with protection, all the mice survive in the Peters test after 20 days with a daily dose of 50 mg/Kg for 4 days.

The dosages used for the compounds of the invention are thus comparable to those used for artemether, or artesunate. 

1. A compound of the formula

in which: R₁ is: a fluoroalkyl group of 1 to 5 carbon atoms, comprising at least two fluorine atoms, selected from the perfluoroalkyl group consisting of CF₃, C₂F₅, C₃F₇, C₄F₉, and C₅F₁₁, or a fluoroaryl group comprising at least two fluorine atoms, selected from the group comprising the perfluoroaryl group C₆F₅, R₂ is a hydrogen atom, a halogen atom, or a group that renders said compound water-soluble, said group derived from piperazine, morpholine, alkylamine, alkoxy, ester or diester, acid or diacid, thioalkyl, alkylhydroxyl, or glycosyl, R₃ is: an OR group, in which R is H, an alkyl group of 1 to 10 carbon atoms or a phenyl group, or NH₂ or a NH—R₆ group, in which R₆ is an alkyl or alkoxy group of 1 to 5 carbon atoms, an arylalkyl group or arylalkoxy group, and is H or OH.
 2. The compound according to claim 1, wherein R₂ is Br.
 3. The compound according to claim 1, wherein R₃ is: an OR group wherein R is a group of formula —(CH₂)_(n)—R₅, in which n is an integer from 1 to 5, and R₅ is: CF₃, OH, —CH═CH₂, COOH, COH, or CHOH—CH₂OH, a phenyl group optionally substituted by CH₂OH, or an —NH—C₆H₅—OCH₃ group.
 4. The compound according to claim 1, in which: R₁ is CF₃, R₂ and R₄ are each independently a hydrogen atom, and said compound corresponds to the formula:


5. The compound according to claim 4, said compound being selected from the group consisting of:


6. A pharmaceutical composition comprising at least one compound according to claim 1, combined with a pharmaceutically acceptable vehicle.
 7. The pharmaceutical composition according to claim 7, in a form adapted for administration by oral, injectable, or rectal route.
 8. The pharmaceutical composition according to claim 6, in unit dose form permitting administering said compounds in an amount of 5 mg to 5 g for a dosage of 1 mg/kg/day to 100 mg/kg/day.
 9. The pharmaceutical composition according to claim 6, characterized further comprising one or more other anti-malarial compounds selected from the group consisting of pyrimethamine, sulfadoxine, quinine, lumefantrine and mefloquine.
 10. A method for the treatment of malaria, said method comprising administering the compound according to claim 1 to a patient in need thereof.
 11. A composition comprising at least one compound according to claim 1 and at least one other anti-malarial compound.
 12. A process for preparing the compound according to claim 1, said process comprising: a) treating an intermediate compound of the formula:

with a nucleophile of formula HO—R, in which R is H, an alkyl group of 1 to 10 carbon atoms or a phenyl group, to obtain the compound of claim 1, in which R₃ is OR, or with acetonitrile to obtain the compound of claim 1, in which R₃ is NH₂, or with NH₂—R₆ in which R₆ is an alkyl or alkoxy group of 1 to 5 carbon atoms, an arylalkyl group or arylalkoxy group, to obtain the compound of claim 1, in which R₃ is —NHR₆, b) agitating at the reaction mixture at room temperature, c) treating the reaction mixture with an aqueous solution of sodium bicarbonate, d) drying, and e) solvent evaporation to obtain the compound of the formula:

in which R₃ is: an OR group, in which R is H, an alkyl group of 1 to 10 carbon atoms or a phenyl group, or NH₂ or a NH—R₆ group, in which R₆ is an alkyl or alkoxy group of 1 to carbon atoms, an arylalkyl group or arylalkoxy group.
 13. The process according to claim 12, wherein step a) is run in hexafluoroisopropanol after solubilisation of the intermediate compound in methanol.
 14. The process according to claim 12, wherein step e) is followed by a purification step. 